Skateboard/longboard truck with advanced pivot mechanism

ABSTRACT

A skateboard or longboard truck comprises a hanger and a baseplate assembly. A redesigned hanger, a large ball pivot, a load-redirecting pivot cup, a tapered kingpin and other improvements give the hanger a high kingpin ratio and a high angle of mechanical advantage, thereby improving the performance and turning characteristics of the truck.

RELATED APPLICATIONS

This application claims the benefit of our U.S. Provisional ApplicationNo. 61/903,790, filed Nov. 13, 2013, and entitled “Skateboard/LongboardTruck With Active Massive Ball Pivot Mechanism,” which is hereinincorporated by reference.

FIELD OF THE INVENTION

The field of the invention is skateboards and longboards, and moreparticularly, trucks for skateboards and longboards.

BACKGROUND

Traditional skateboard truck assemblies accomplish the action of turningwhen the rider shifts his weight on the skateboard deck from neutral toeither side of the skateboard's longitudinal axis.

Consistent with FIG. 1 a complete skateboard assembly consists of twoskateboard trucks with four attached wheels that are attached to askateboard deck. Each skateboard truck comprises a baseplate assembly,which is attached to the deck, and a hanger assembly on which the wheelsare hung.

As a rider leans the skateboard deck from side to side, the axleintegral to the skateboard truck hanger assembly is forced to stayparallel to the ground as long as the weight of the rider forces thewheels to remain in contact with ground. Rotation of the skateboard deckaround an axis parallel to the longitudinal centerline of the skateboarddeck causes the skateboard truck hanger assemblies to rotate—whilestaying parallel to the ground—about other axes, resulting in a turningaction transmitted through the skateboard truck assemblies.

Furthermore, when the deck of a typical skateboard is rotated, it causesthe hanger assembly to rotate about an axis between the center of theextreme end of the pivot and a point in the center of the hangeraperture coincident with the longitudinal centerline of the kingpin.This causes fore and aft movement of the hanger and the wheels attachedto it relative to the neutral position of the trucks when the deck isevenly weighted and parallel to the ground. As the rider angles thedeck, the wheels proximate to the weighted side that is angled towardthe ground move toward the middle of the skateboard deck, and the wheelson the opposite side from the weighted edge of the deck move away fromthe middle of the skateboard deck toward the ends of the skateboarddeck. The result is that the trucks allow the rider to turn theskateboard by converting the force created by the leaning of theskateboard deck into a controlled turning action. The turning action isaccomplished by the fore and aft movement of the wheels attached to theskateboard trucks as they rotate on the kingpin which is oriented at anangle less than 90 degrees to the ground plane (FIG. 8).

SUMMARY

A skateboard or longboard truck is provided that comprises a hanger anda baseplate assembly. The hanger includes a structural axle-bearingmember and a pivot extending out perpendicularly from the structuralmember, a bushing seat and kingpin aperture located between thestructural member and the pivot. The hanger is oriented along a lateralaxis and configured to support two wheels. The baseplate assembly has abase that mounts underneath a skateboard or longboard deck. Thebaseplate assembly also has a mounting flange configured to receive akingpin to secure the hanger assembly to the baseplate assembly.

In one aspect of the invention, the hanger is configured with a massiveball pivot. The size and configuration of the ball pivot improves theturning responsiveness of the truck to loads it receives from theskateboard or longboard truck and the ease with which a skateboarder cancontrol the turns.

In another aspect of the invention, a pivot cup is configured to receivethe ball pivot. The pivot cup is formed with a bottom hole or pocketthat is configured to avoid contact with a bottom surface area portionof the ball pivot of at least approximately 0.6 steradians. Thisconfiguration redirects loads that would otherwise concentrate at thebottom of the cup to the sides of the cup, further improving the turningresponsiveness of the truck.

A further aspect of the invention is the provision of a tapered kingpin.The kingpin has a head joined to a shaft. A section of the shaftproximate to the head is tapered, so that the shaft has a first diameterproximate to the head that tapers down to a smaller second diameter at adistal portion of the shaft immediately prior to the portion of theshaft that passes thru the elastomeric bushings.

BRIEF DESCRIPTION OF THE DRAWINGS

The benefits, features, and advantages of the present invention willbecome better understood with regard to the following description, andaccompanying drawings where:

FIG. 1 is a perspective view of a complete skateboard or longboardassembly

FIG. 2 is a perspective view of one embodiment of a skateboard orlongboard truck according to the present invention.

FIG. 3 is an exploded perspective view of one embodiment of a skateboardor longboard truck according to the present invention.

FIG. 4 is a perspective view of a hanger assembly of the truck of FIG.2.

FIG. 5 is a perspective view of a baseplate assembly of the truck ofFIG. 2,

FIG. 6 is a top view of the hanger assembly of the skateboard truckassembly of FIG. 2, illustrating dimensions that factor into the kingpinratio, the angle of mechanical advantage, and center of pressure.

FIG. 7 is a side section view of the truck assembly of FIG. 2, whichillustrates the kingpin and baseplate angles of the truck, dual axes ofrotation, and pivot load transfer.

FIG. 8 is a bottom view of the skateboard assembly of FIG. 1,illustrating the relation between deck angle and truck turning angle.

FIG. 9 is a perspective view of the pivot cup of FIG. 3,

FIG. 10 is top view of the pivot cup of FIG. 3, illustration the airgap.

FIG. 11 is a perspective cut-away view of the pivot cup of FIGS. 3 and10, illustrating the threaded airgap and cleaning grooves

FIG. 12 is a side view of the pivot cup of FIGS. 3, 10, and 11, showingthe tolerance fin.

FIG. 13 is a perspective view of the kingpin of FIG. 3.

FIG. 14 is a top view of the kingpin of FIG. 3, illustrating the taperedsection of the shaft.

FIG. 15A is a view of the hanger assembly of FIG. 3 while articulated,as it would characteristically be if the skateboard or longboard deckwere bearing a statically unbalanced load.

FIG. 15B is a detail view of the ball pivot and pivot cup of FIG. 16A,showing the non-interference zone of the ball pivot and pivot cup.

FIG. 16A is a top view of a prior art hanger while articulated, as itwould characteristically be if a skateboard or longboard deck to whichit were coupled were bearing a statically unbalanced load.

FIG. 16B is a top detail view of the prior art pin pivot and pivot cupof FIG. 16A, illustrating the interference zone of the pin pivot andpivot cup.

FIG. 17 is a side view of the baseplate of FIG. 3, showing the taperedwalls and kingpin support section.

FIG. 18 is a sectional view of the hanger assembly along the line 1-1 ofFIG. 3 in the direction of the arrows, illustrating the bushing seat.

FIG. 19A is a top view of a prior art skateboard truck assembly withwheels mounted.

FIG. 19B is a detailed top view of a prior art skateboard truck assemblywith wheels mounted showing the need for two axle washers to create thenecessary separation between the outer bearing race and face of thestructural member.

FIG. 20A is a top view of the skateboard truck assembly with wheelsmounted.

FIG. 20B is a detailed top view of the skateboard truck assembly withwheels mounted showing that the integral bearing standoffs create thenecessary separation between the outer bearing race and face of thestructural member.

DETAILED DESCRIPTION

The following description is presented to enable one of ordinary skillin the art to make and use the present invention as provided within thecontext of a particular application and its requirements. Variousmodifications to the preferred embodiment will, however, be apparent toone skilled in the art, and the general principles defined herein may beapplied to other embodiments. Therefore, the present invention is notintended to be limited to the particular embodiments shown and describedherein, but is to be accorded the widest scope consistent with theprinciples and novel features herein disclosed.

The invention relates to a mechanism known in general terms as askateboard truck. A skateboard truck connects wheels to a skateboard orlongboard deck allowing articulation of the wheels attached to theskateboard truck by application of the rider's weight to one side of thedeck (FIG. 8). Application of weight to the edge of the skateboard deckallows the skateboard to be turned as the articulation of the deckconverts deck angle changes into fore and aft movement of wheelsattached to the skateboard truck. The invention improves on prior art inmultiple ways, including an improved functional geometry, improvedstructural design, improved constructability, improved maintainability,and improved durability resulting in smoother and more responsive orimmediate turning performance.

The skateboard truck is comprised of two major assemblies, the ballpivot hanger assembly and the baseplate assembly. The assemblies aremechanically joined together and retained by a kingpin washer,elastomeric bushings, and kingpin nut (FIG. 1).

The hanger assembly is comprised of the hanger body, axle, axle washersand axle nuts. The body of the hanger incorporates a structural memberoriented along a lateral axis perpendicular to and distal from the ballpivot. An axle made of a dissimilar material passes through the beamsection of the body parallel to the beam. Alternatively, the axle may bemade of two segments that pass into but not through the beam. On eachend of the axle or axles there is an axle nut and axle nut washer. Theball pivot may be an integral part of the hanger body or may be aseparate attached component. The ball pivot is formed so that it mayrotate in a similar sized pivot cup by at least about twenty degrees inany direction without making contact with the pivot cup wall (FIG. 15).The ball pivot has a diameter that is preferably at least 13 mm indiameter. There is an aperture in the hanger assembly body through whicha kingpin passes that is located between the axle or axles and the ballpivot. The aperture has two elastomeric bushing seats that areconcentric with the aperture and centerline of the kingpin. The bushingseats are located above and below the aperture (FIG. 3).

The baseplate assembly is comprised of a baseplate body, pivot cup and atapered kingpin. The baseplate body has a pivot cup cavity in itsforward section into which a removable friction fit pivot cup isinstalled. There are holes drilled into both sides of the baseplate bodythat are used to provide a means of attachment for the baseplate to theskateboard deck using fasteners.

The pivot cup that is installed in the baseplate cavity bore provides aload bearing surface for the hanger assembly ball pivot. The pivot cupis designed to transmit loads from the ball pivot to the side-walls ofthe baseplate pivot cup cavity. The outside surface of cylindricalsection of the pivot cup includes retention fins or rings that providefor a friction fit allowing friction based retention of the pivot cup inthe pivot cup cavity. The exterior bottom surface of the pivot cup isangled so that no surface is more than fifty degrees off a line runningthrough the center of the pivot cup hole in the bottom of the pivot cupand the center of the hanger-body bushing aperture. The bottom of thepivot cup is more steeply angled than prior art to allow the cup tocompress down and toward the center of the pivot cup cavity in thebaseplate. The inside contours of the pivot cup include self-cleaninggroves that are designed to remove dirt or debris from the ball pivotwhen the ball pivot rotates. In the center bottom of the pivot cup thereis a hole that provides a void for the pivot cup to compress down andinto the bottom of the baseplate pivot cup cavity. The hole in thebottom of the pivot cup is also is designed to collect debris as part ofthe pivot cup's self-cleaning function and if threaded to provide for ameans of threaded mechanical extraction using a threaded shaft or theaxle of the hanger assembly.

There is a kingpin support structure on the rear of the baseplate bodythat contains a tapered bore-hole into which the tapered kingpin isinstalled. The kingpin is a separate component that is inserted into thebaseplate's tapered kingpin bore hole as part of the overall baseplateassembly. The kingpin has a tapered section proximate to the end of thekingpin where the head is designed to prevent rotation. The section inthe middle of the kingpin where elastomeric bushings are later installedis of constant diameter that is smaller than the maximum diameter of thekingpin proximate to the head. The end of the kingpin distal from thehead of the kingpin has threads that engage a kingpin nut. The kingpinrelies on an enlarging taper proximate to the head of the kingpin thatmatches the angle of taper found in the kingpin bore hole for itsmechanical connection to the baseplate. The taper provides for kingpinretention and load transfer to the baseplate through the sidewalls ofthe tapered kingpin bore hole. Rotation of the tapered kingpin isprevented by trapping the head of the kingpin on the side of the kingpinbore hole that is distal from the side of the kingpin bore hole that isadjacent to the lower elastomeric bushing bearing surface.

The ball pivot hanger assembly is installed in the baseplate assembly byfirst placing the lower elastomeric bushing on the kingpin in contactwith the adjoining baseplate bearing surface. The second step is toconcurrently insert the ball pivot on the hanger assembly into thebaseplate pivot cup while lowering the hanger assembly over the kingpinuntil the lower bushing seat on the hanger assembly has fully engagedthe lower elastomeric bushing. Next, the upper elastomeric bushing isplaced over the kingpin and seated into the upper bushing seat of theball pivot hanger assembly. A bushing washer is placed on top of theupper elastomeric bushing. Finally a kingpin nut is threaded onto thekingpin resulting in compression of the bushing washer and theelastomeric bushings. (FIG. 1).

When fully assembled, the hanger assembly is sandwiched on both sides ofthe kingpin aperture by two elastomeric bushings, a kingpin washer andkingpin nut in a manner that allows the rider to adjust the level ofpressure on the elastomeric bushings to increase or decrease the levelof force required to angle the skateboard deck. The functional assemblytraps the ball pivot on the hanger assembly in intimate contact with thepivot cup in the baseplate so that the ball pivot hanger assembly canrotate without interference and transfer loads effectively into the sidewall of the baseplate as the mechanism is rotated from side to side(FIGS. 3, 38).

The drawings, with the exception of those labeled “prior art,”illustrate an embodiment of a skateboard truck 10 comprising a ballpivot hanger 15, a baseplate assembly 115, a pivot cup 155, a kingpin210, bushings 242 and 245, and various fastening members, includingwashers 250, 36 and nuts 255, 37.

Geometry

The skateboard truck 10 improves upon previous skateboard truck designsby changing the geometry and design of one or more key elements of theskateboard truck 10. Several of these improvements contribute to a highlevel of mechanical advantage 295 and improved turning function. Theseimprovements include a larger diameter ball pivot 65, effective transferof ball pivot loads 142 into the side of the pivot cup cavity 140,precision bushing seats 40, the physical form of the baseplate 115 andthe hanger 15, and a tapered kingpin 210. The improvements, whetherconsidered singly or more preferably in combination, improve ridingperformance, mechanical function, durability, constructability andmaintainability. It should be understood that the invention encompassesnot only the synergistic combination of these various improvements, butalso sub-combinations and single ones of these improvements.

Ball Pivot Hanger

FIGS. 2-4, 6 and 20 illustrate one embodiment of a ball pivot hanger 15.The ball pivot hanger 15 comprises a structural member 20, an integralaxle 30 (or a pair of axles 30 mounted in the ends of the beam 20),bushing seats 40, and a ball pivot 65. The structural member 20 has aform determined by the principles of a wide flange I-beam. Reliefs 28strategically reduce the mass and weight of the hanger 15 with minimumimpact on the hanger's 15 strength. The structural member 20 is orientedto span the widest direction of the hanger 15. The integral axle 30, oraxles 30 if separate axles are utilized, optionally made of a dissimilarmaterial, runs from one end of the beam 20 to the other protruding so asto provide a mounting location for skateboard wheels 325.

The ball pivot hanger 15 includes two axle bearing spacing steps orbosses 35 (e.g., machined features at opposite distal ends of thestructural member 20). Each boss 35 creates a separation 31 between theaxle bearing surface 32 and the face 33 of the structural member 20within which the axle 30 is contained so as to provide a bearingstandoff that eliminates the need for an axle washer 36 known as aspeedring. The boss 35 supports the central race 34 of the bearing andprevents the outer race 39 from making contact with the adjoiningstructural member 20. Alternatively, the structural member 20 thatembraces the axle 30 (or pair of axles 30) includes two bearingstandoffs 35 that separate a bearing surface 32 of the structural member20 from a non-bearing surface of the face 33 of the structural member 20that embraces the axle 30. The standoff may also be an additionalcomponent that is attached to the structural member 20 or axle 30.

Concentric top and bottom bushing seats 40 extend outwardly from amidsection of the structural member 20 and provide a zero tolerance fitfor elastomeric bushings 242, 245. An aperture 45 formed through thecenters of the bushing seats 40 receives a kingpin 210 to mount thehanger 15, sandwiched between the two elastomeric bushings 242, 245 tothe baseplate 115. An aperture 45 in the hanger 15 between the ballpivot 65 and the axle 30 allows a kingpin 210 to pass through the hanger15 to assemble the hanger 15 to the baseplate 115.

Ball Pivot

FIG. 15 illustrates one embodiment of a ball pivot 65 incorporated intoa hanger 15. The ball pivot 65 extends perpendicularly out from themidsection of the structural member 20 and axle 30 and is, in oneembodiment, preferably cast, forged, or machined as an integral part ofthe hanger 15 (FIG. 6). The ball pivot 65 located on the hanger 15differs from other traditional pin pivot or ball designs due to its muchlarger diameter 75, preferably at least 13 mm, and resulting largerbearing surface. The ball pivot's 65 larger surface area combined withthe pivot cup 155 and baseplate 115 design allow for pivot loads 142 tobe transferred into the side wall 147 and tapered cavity walls 145 ofthe baseplate pivot cup cavity 140 instead of the bottom of the pivotcavity 140 as is typical with prior art (FIG. 16). The design of theball pivot 65 transfers turning load from the ball pivot 65 to the sidewall 160 of the pivot cup 155 at a point much closer to the kingpin 210compared to the small diameter ball or pin pivots 85 of many otherdesigns, that transfer load from the pivot 85 to or near the bottom 102of the pivot cup 103 through the end 95 of the pivot 85 distal to theaxle. The large diameter ball pivot hanger 15, pivot cup design 155,tapered kingpin 210 and baseplate 115 design act synergistically toachieve improved turning performance.

The ball pivot 65 provides unrestricted movement when compared to priorart pin pivots 85 that are not designed to accommodate significantunrestricted rotation on two planes as the skateboard truck 320 isarticulated. The ball pivot 65 provides unrestricted turning actionwithin at least about ten degrees from a neutral center line 300 thatpasses through the center of rotation 70 and a point 60 coincident withthe center of the kingpin aperture 45 and the longitudinal center 212 ofthe kingpin 210 (FIGS. 7, 13-14). Unrestricted turning action within thenon-interference area 80 (FIG. 15) is achieved due to an absence ofmechanical interference with the pivot cup side wall 160 or progressiveresistance from the compression of an elastomeric pivot cup 100 as iscommon with prior art designs (FIG. 16). This improvement alsoeliminates the stress and mechanical wear that takes place with manyconventional pin pivot 85 designs when they make physical contact withthe wall of the pivot cup or pivot cup cavity. The ball pivot 65 on thehanger 15 in conjunction with the pivot cup 155 is configured to provideconstant low-friction intimate contact between the pivot cup 155 and theball pivot 65 allowing the ball pivot 65 to pass its loads through thesidewalls 160 of the pivot cup 155 and then directly into the side wall160 of the baseplate pivot cup cavity 140.

Pivot Cup

FIGS. 9-12 illustrate one embodiment of a pivot cup 155. The pivot cup155 is installed in the baseplate pivot cup cavity 140. The pivot cup155 comprises an internal pivot-bearing surface area 165 defined bycurved cylindrical interior sidewalls 160, a cylindrical outer topsurface 162, a ramped outer bottom surface 170, cleaning grooves orchannels 180, retention fins or rings 195, 200, and a ramping tolerancefin 205. The pivot cup 155 is formed with a bottom center hole or pocket185 that is configured to avoid contact with a bottom surface areaportion of the ball pivot 65 of at least approximately 0.6 steradians.This causes pivot loads 177 to be transferred into the side wall 147 ofthe baseplate pivot cup cavity 140 instead of the bottom of the pivotcavity as is typical with prior art (FIG. 16).

The pivot cup 155 provides a load bearing low friction constant contacttransfer surface between the ball pivot 65 and the baseplate pivot cupcavity side wall 147. The pivot cup 115 may be composed of nylon, POM(acetyl), PU (Polyurethane) or other suitable low friction, bearingsurface materials. The cylindrical outer top surface 162 of the pivotcup 155 contains fins or rings 195, 200, 205 designed to compensate fordimensional tolerance variations between the pivot cup 155 and the pivotcup cavity 140. The fins 195 retain the pivot cup 155 in the pivot cupcavity 140 and prevent pivot cup 140 rotation. The pivot cup's outerbottom surface 170 is angled to match the bottom portion 145 of thebaseplate pivot cup cavity 140 (FIG. 7). This angle provides a rampingforce toward the center of the pivot cup cavity 140 when the pivot cup155 is pressed into the cavity 140. The ramping force is present whenthe truck 10 is in use and loads are applied via the rider's weightthrough the ball pivot 65 on the hanger 15. The ramping action isdesigned to center and compress the pivot cup 155 in the baseplate pivotcup cavity 140.

The interior sidewalls 160 of the pivot cup 155 contain grooves orchannels 180 designed to provide a self-cleaning action relative to thesurface of the ball pivot 65 as it rotates in the pivot cup 155 (FIG.10, 11). The pivot cup 155 contains a hole 185 in its center so that asthe pivot cup 155 is driven into the pivot cup cavity 140 by the rampingaction it can compress without interference inward toward the center ofthe pivot cup cavity 140, ensuring intimate contact between the internalpivot-bearing surface area 165 of the pivot cup 155 and the ball pivot65. The center hole 185 in the bottom of the pivot cup 155 also servesto provide self-cleaning, debris retention and threaded mechanicalextraction functions. The pivot cup's center hole 185 may be threaded,allowing mechanical extraction of the pivot cup 165 from the pivot cupcavity 140 using a threaded rod or hanger axle 30 (FIG. 4). Prior artpivot cups are made of soft elastomeric material and do not incorporateself-cleaning, self-centering, tolerance absorbing components, aprovision for mechanical removal using threaded tools, or steep rampingsurfaces

Baseplate

FIGS. 5, 7 and 17 illustrate one embodiment of a baseplate 115. Thebaseplate 115 comprises a flanged base 116, a kingpin support structure224, and a pivot cup cavity bore 140. The pivot cup cavity bore 140,located at a forward section of the baseplate 115, is drilled at angleparallel to the primary or first axis 300 of rotation of the hanger 15.The top portion 147 of the pivot cup bore 140 is defined bycylindrically shaped walls. The bottom portion 145 of the pivot cup bore140 is defined by conically shaped tapered cavity walls angled no morethan fifty degrees off of the primary rotational axis 300. Accordingly,the opening angle 149 formed by the tapered cavity walls is no greaterthan one hundred degrees. The steep tapering of the cavity walls use theforce from the rider's weight that is applied via the ball pivot 65 todrive the pivot cup 155 into the angled bottom portion 145 of the pivotcup cavity bore 140. The ramped outer bottom surface 170 of the pivotcup 140 is configured with angles that match the angle of the bottomportion 145 of the pivot cavity bore 140 and allows for pivot cupcompression into the pivot cup cavity bore 140. Compression of the pivotcup 155 aids in preserving the constant center of rotation 70 allowedfor by the ball pivot 65.

Also unlike prior art, on the rear section of the baseplate 115 there isa section of the body through which a tapered borehole 211 provides asupport structure for the tapered kingpin 210. The diameter 214 of thekingpin bore 211 hole proximate to the bolt head 215 is larger than thebore diameter 213 distal to the bolt head 215 (FIG. 17). The lowersection 222 of the kingpin support structure 224 includes a channel 218that is used to prevent rotation of the kingpin's head 215 when thekingpin nut 255 is tightened to adjust bushing 242, 245 tension. Theupper section 223 of the kingpin bore hole 211 is designed to functionas a seat for the lower elastomeric bushing 242. The flanges 116 of thebase extend along both sides of the baseplate 115. The flanges 116contain holes 117 that provide a means to use fasteners 326 (FIG. 1) toattach the baseplate 115 to the skateboard deck 330 (FIG. 5, 7, 17).

Kingpin

FIGS. 3, 7, and 13-14 illustrate one embodiment of a tapered kingpinassembly 207. The tapered kingpin assembly 207 comprises a taperedkingpin 210, a kingpin bushing washer 250, two elastic bushings 242,245, and a nut 255. The tapered kingpin 210, which comprises a head 215connected to a shaft 220, is used to connect the hanger 15 to thebaseplate 115. The tapered kingpin 210 is removable with no damage tothe baseplate assembly 115 and achieves a zero clearance fit whentightened into a matching tapered baseplate kingpin borehole 211. Whentightened by the compression of the kingpin nut 255 against the kingpinbushing washer 250 and two elastomeric bushings 242, 245, the kingpin210 acts as a rigid and integral component of the baseplate 115. Thisincreased rigidity of the baseplate 115 and kingpin assembly 207 resultsin improved turning performance by eliminating rocking or working of thekingpin 210 back and forth in a traditional kingpin borehole.

Prior art includes two primary styles of kingpins. Kingpins that wereintended to be removable were based on a simple bolt design withdimensional tolerances that resulted in movement of the kingpin fromside to side in the kingpin baseplate bore hole as the truck wassubjected to turning actions. Alternatively kingpins used in some priorart skateboard trucks incorporated barbed or splined driven bolts thatwere driven into the kingpin borehole. The splined or barbed bolt designwas not easily removable and the process of removal and reinstallationwould frequently result in damage to the kingpin bore hole that wouldfurther allow the kingpin to work back and forth as the deck angle waschanged. Both the traditional bolt and barbed or splined prior artkingpin designs resulted in degraded truck performance, constructabilityand or maintainability.

The kingpin shaft 220 includes a middle tapered section 225. Theremaining one or more sections of the shaft including the threaded end240 and the constant diameter, are untapered. The tapered portion 225 ofthe kingpin 210 is located along a portion of the shaft that, whenassembled, makes contact with the tapered baseplate borehole 211. Thetapered portion 225 of the kingpin 210 is distal from the threaded end240 of the kingpin 210 and proximate to the polygonal head 215. Thediameter 230 of the kingpin 210 gets progressively smaller as onetravels the length of the tapered section 225 of the shaft 220 from thetop end of the tapered section 225, proximate to the polygonal head 215,toward the bottom end of the tapered section 225, relatively moreproximate to the bolt threads 240. The diameter 227 of the kingpin 210is constant in the un-tapered sections 227 of the shaft 220 which arenot designed to engage the baseplate tapered borehole 211, includinglocations where the kingpin 210 passes through the elastomeric bushings242, 245 (FIG. 7, 13, 14).

The tapered kingpin 210 can be inserted into the tapered baseplate borehole 211 until the increasing diameter of tapered kingpin 210 exceedsthe matching maximum tapered borehole diameter 213, 214. The kingpin 210seats in the tapered borehole 211 with an intimate, zero clearance fitbecause the kingpin 210 always tapers to a diameter 230 larger than thelargest tapered kingpin bore diameter 213 in the baseplate 115. Thetapered shaft 225 of the kingpin 210 is designed retain the kingpin 210with the head 215 of the kingpin 210 slightly out of contact with theside of the tapered baseplate borehole 130 that is opposite from theside 241 where the elastomeric bushings 242, 245 seat (FIG. 7, 17, 13,14).

The tapered kingpin 210 and tapered kingpin bore hole 211 provide aprecision zero clearance kingpin fit in the baseplate kingpin taperedbore hole 211 while allowing for easy removal without damage to thekingpin 210 or kingpin borehole 211. Because the kingpin 210 is inintimate contact with the tapered sidewalls 226 of the baseplate 115,the baseplate 115 and kingpin 210 act as one unit transmitting forcesprecisely and immediately from the changing deck angle 318 into thetruck assembly 10 (FIG. 7, 17, 13, 14).

Center of Rotation

The location of the center of rotation 70 of the ball pivot 65 (FIG. 6)is different from prior art. The center of rotation 70 of the ball pivot65 (FIG. 6), and the center of rotation 95 of a conventional prior artpin pivot 85, are both herein defined as a point within or upon thesurface of the pivot 65, 80 that translates the least, with respect tothe baseplate, as the pivot 65, 80 rotates within a similarly sizedpivot cup 155. The larger diameter ball pivot 65 combined with the pivotcup 155 and baseplate 115 designs move the center of rotation 70 closerto the center of the kingpin aperture than is found in prior artdesigns. The center of rotation 70 is in the geometric center of theball pivot 65. Prior art designs have pin or ball pivots that aretypically less than 13 mm in diameter. The center of rotation 95 forprior art pin or ball pivots is the center of the pivot radius proximateto the end of the pivot. Due to the small pivot diameter and the useflexible low-durometer pivot cups (e.g., below 95 a durometer), theseprior art designs transfer load thru the end of the pivot by bearing onthe bottom of pivot cup. In most cases the use of a small diameter pivotand an elastomeric pivot cup does not provide for a constant centerrotation (FIG. 6, 15, 16).

Center of Pressure

The center of pressure 83 (FIG. 6) for the ball pivot 65 is the locationon the ball pivot's face central to where the greatest load istransmitted through the walls of the pivot cup 155. As a result ofmoving the center of rotation 70 of the ball pivot 65 back to a pointequidistant from all sides of the ball pivot's 65 rotating sphere, thecenter of pressure 83 also moves back and to the side of the ball pivot65 relative to traditional pin pivot or ball pivot designs 65. Whenturning the truck 10, the center of pressure 83 is applied against theside 147 of the pivot cup cavity 140 at a point that is significantlydistal from the bottom of the pivot cup cavity 140. The center ofpressure for prior art pin or ball pivots, by contrast, is concentratedproximate to the bottom of the pivot cup cavity.

Angle of Mechanical Advantage

Various aspects of the invention contribute to the truck's high andconsistent mechanical advantage 295 in translating and amplifying theforce a rider exerts on the deck into a force that turns the truck (FIG.6). One influential contribution to the truck's mechanical advantage isthe angle 295 between two lines, referred to herein as the “angle ofmechanical advantage.” The first line is the primary rotational axis 300that runs between the center 60 of the kingpin aperture 45 and the ballpivot's constant center of rotation 70 (FIG. 7). The second line 297runs between an outermost contact point 298 of the ball pivot 65 withthe pivot cup 155 and the opposing outermost bearing surface 299 of thebushing seat 40 that retains the elastomeric bushing 242, 245 laterallyin the hanger 15. Stated another way, the angle of mechanical advantage295 is approximately equal to an inverse tangent of the sum of the ballpivot radius and the kingpin bushing radius divided by theball-pivot-center-to-kingpin-center distance. A higher angle ofmechanical advantage 295, one that is, for example, at least twenty andpreferably at least twenty-five degrees, significantly improves therider's ability to compress the elastomeric bushings 242, 245 andmagnifies the turning action of the truck 10 when compared with priorart designs. Additionally, the higher level of mechanical advantage 295allows the truck 10 to rotate on two planes concurrently.

The proximity between the center of rotation 70 of the ball pivot 65 andthe center 60 of the kingpin aperture 45, the diameter 75 of the ballpivot 65, the diameter 41 of the bushing seat 40, and the lack ofmovement achieved by the tapered kingpin 210 all combine to influencethe angle of mechanical advantage 295 and the overall effective leveragethe rider achieves against the elastomeric bushings 242, 245. A highmechanical advantage 295 without pivot cup 155 restriction alsofacilitates a more dynamic turning response characteristic.

King Pin Ratio

Another contribution to the truck's mechanical advantage is the kingpinratio (FIG. 6). The kingpin ratio 290 is defined by the distance 291between the kingpin aperture center 60 and longitudinal axle centerline270 divided by the distance 292 between the ball pivot center 70, or theconstant center of rotation 70 and the kingpin aperture center 60. Thehanger 15 has a kingpin ratio 291, expressed as a percentage, offifty-two percent or more. A higher percentage kingpin ratio, inaddition to a high angle of mechanical advantage, contributes to thetruck's greater mechanical advantage relative to prior art designs.

Concurrent Rotation on Two Axis

The ball pivot hanger 15 rotates concurrently around two axes 300, 305(FIG. 7). The first axis 300 is between the constant center of rotation70 of the ball pivot 65 and the kingpin aperture center 60. The secondaxis 305 is parallel to the longitudinal centerline 212 of the kingpin210 and runs thru the constant center of rotation 70 of the ball pivot65. This second axis 305 allows the hanger 15 to shift from side to siderelative to the kingpin 210 while concurrently rotating relative to thefirst axis 300 with no pivot cup 155 or pivot cup cavity interference140. To rotate around the second axis 305, the bushings 242, 245 must becompressed parallel to the kingpin bore hole 211 and the hanger bushingseat retention wall 43. Any change in deck angle results in both avertical compression and horizontal compression of the bushings relativeto the kingpin (FIG. 7).

Riding Benefit of Design

All of the forces that compress the bushings 242, 245 and result in thearticulation of the hanger 15 are from the rider's weight. All of therider's weight is supported by the four wheels 325 mounted on the twoaxles 30. A larger distance 291 between the axle 30 and kingpin aperturecenter 210 in relation to the distance 292 from the kingpin aperturecenter 210 to the constant center of rotation 70 results in greatermechanical advantage. A greater mechanical advantage results in moreleverage acting on the bushings 242, 245. With more leverage on thebushings 242, 245, the rider is able to more effectively rotate thehanger 15 around the first 300 and the second axes 305. Because of thisincreased mechanical advantage 295, the lack of pivot interference withthe pivot cup 155 or baseplate pivot cup cavity 140, and the ability torotate the hanger 15 concurrently around two axes 300, 305, immediatearticulation is achieved resulting in improved turning performance.

Although the present invention has been described in considerable detailwith reference to certain preferred versions thereof, other versions andvariations are possible and contemplated. Those skilled in the artshould appreciate that they can readily use the disclosed conception andspecific embodiments as a basis for designing or modifying otherstructures for carrying out the same purposes of the present inventionwithout departing from the spirit and scope of the invention as definedby the appended claims.

We claim:
 1. A skateboard or longboard truck comprising: a hangerincluding a structural member oriented along a lateral axis andconfigured to support two wheels and a pivot extending out from thestructural member in a direction perpendicular to the structural member;and a pivot cup configured to receive the pivot; wherein the pivot cupis formed with a bottom hole or pocket that is configured to avoidcontact with a bottom surface area portion of the pivot of at leastapproximately 0.6 steradians.
 2. The skateboard or longboard truck ofclaim 1, further comprising a baseplate configured for attachment to askateboard or longboard, the baseplate providing a pivot cup cavity forseating the pivot cup and a bore for mounting a kingpin; wherein thehanger provides a kingpin aperture for receiving the kingpin, and thepivot cup has a ramped outer bottom surface, ramped at an angle of nomore than fifty degrees relative to a centerline passing between thecenter of rotation and a point coincident with the center of the kingpinaperture and the longitudinal centerline of the kingpin, to cause thepivot cup to self-center and tighten in the pivot cup cavity under load.3. The skateboard or longboard truck of claim 1, wherein the pivot cuphas an internal pivot-bearing surface area that is formed with groovesor channels to channel dirt and debris away from the surface of thepivot and pivot cup bearing surface when the pivot is rotated in thepivot cup.
 4. The skateboard or longboard truck of claim 1, furthercomprising a baseplate configured for attachment to a skateboard orlongboard, the baseplate providing a pivot cup cavity for seating thepivot cup; wherein the bottom hole or pocket of the pivot cup isconfigured to allow compression of the pivot cup into the pivot cupcavity when forces are applied to the pivot by a rider's weight so as toprovide a cushioning, self-centering, and self-tensioning effect on thepivot cup in the pivot cup cavity when subjected to normal riding loadstransmitted through the pivot.
 5. The skateboard or longboard truck ofclaim 1, further comprising a pivot cup cavity for seating the pivotcup, and wherein the bottom hole or pocket is threaded to facilitateextraction of the pivot cup from the pivot cup cavity.
 6. The skateboardor longboard truck of claim 5, wherein the hanger has an axle formounting wheels and threaded axle ends for securing the wheels to theaxle, and the bottom hole or pocket of the pivot cup is threaded withmatching threads to enable it to be removed with one of the threadedaxle ends of the hanger.
 7. The skateboard or longboard truck of claim1, wherein the bottom hole or pocket in the pivot cup also facilitatescollection of dirt from self-cleaning channels.
 8. The skateboard orlongboard truck of claim 1, wherein the pivot cup is formed withintegral retention fins or rings.
 9. A skateboard or longboard truckcomprising: a hanger having a pivot, a structural member for bearingwheels, and an aperture for a kingpin; the kingpin having a head joinedto a shaft, wherein a section of the shaft proximate to the head istapered, so that the shaft has a first diameter proximate to the headthat tapers down to a smaller second diameter at a distal portion of theshaft immediately prior to another portion of the shaft that passesthrough elastomeric bushings; and a baseplate assembly, the baseplateassembly having a plate portion configured to be fastened to askateboard or longboard deck and a tapered bore configured to seat thekingpin to secure the hanger to the baseplate assembly.
 10. Theskateboard or longboard truck of claim 9, where the kingpin's firstdiameter is larger than a largest diameter of the tapered bore in thebaseplate assembly.